Forming Screw Heads

Hi All

Anybody out there made any screw heads in the workshop by forming, ie by cold heading or upset forging type of techniques.

I need to make some fairly long special 10BA screws and obviously the shaft is too small to turn and hence I need to make the head by hitting it.

I've tried to make some simple tooling and make the head in one hit, but I had a variety of issues ranging from malformed heads to the part sticking in the tool. Nearly there, but no coconut.

So has anybody managed to do this in the workshop and if so, what was the design / principle of the tooling ?

Cheers - Will

Hi Will

Take a chink of scrap steel shaft or a block, say 50mm long

Drill and ream if you have a reamer a 12mm by 50mm through hole in it. the hole size does not matter much as long as it is bigger than the head you intend to make. and you have matching silver steel.

Prepare two 60mm lengths of silver steel rod one with a through hole for the threaded rod (Maybe with a screwed in back stop to set the length) if it ever gets stuck you can remove the back stop and drive it out. Alternatively make the rod the correct length and place that on an anvil of some sort as a back stop. If you do use a screwed in back stop you will need an anvil with a hole to clear the adjustment screw while still supporting the silver steel rod around the edge, this will avoid damaging adjustment the screw.

The other has the end turned to fit your head profile.

Harden the two rods on the business end only.

To use place the piece of rod to be cold headed in position set the two rods roughly centred within the die on an anvil and wallop!

I used a die set just like this to "upset" some 10mm Miniature key rings for a project, I cut them two turns at a time from a commercial wire spring. Nice key rings have the centre upset so that the ends are tucked against the kink.
I could not find a source that was not stainless steel The job needed steel. The ends of the two rods were recessed to fit the ring. The spring was already hardened so it was rough on the dies but "I goter done".

This is a good method for a cheap use once die set.

Regards
John

Edited By John McNamara on 26/11/2013 02:01:23

PS:

If the material you are "cold heading" is inclined to work hardening It may help to heat it up to cherry reed and let it cool in some dry sand, to stop it getting a chill. You may even have to do this a couple of times. while you are forming the head shape. Although I doubt that will be necessary,.most of the BA series is pretty small, a few taps with a hammer should do it.

Gee there are many ways to skin a.......

Regards
John

Hi Will,
You could make the heads as a separate part and silver solder them on provided you do not mind the visible line of the silver solder. The heads could either just have a plane hole and silver soldered in some kind of jig or screwed on with the threads made very loose so there is room for the silver solder. whichever way you make them you will need a very thin slitting saw to cut the slots in the heads.

Les.

Will,

Consider these questions:

1. Is it essential for screw and head to be in one piece?
2. How small must the head be?
3. Do you need a particular style of head?

If the answers are convenient, then it may be easier to fabricate the screws

Simply drill a piece, and fix this to your thread with either 638 Loctite, or Silver Solder.

MichaelG.

.

Edit: Les beat me to it.

Edited By Michael Gilligan on 26/11/2013 08:41:55

Hi All

Really appreciate the suggestions, thanks.

John, the construction of the tool you described is very neat and solves one the key issues I had. I'm going to give that a go and post the results (or perhaps the screws in two parts if they go wrong again !!)

Cheers - Peter

hi peter,

10BA screw are quite fine. i wouldnt dream of bashing the heads. i would machine to size between centres. my lathe is very accurate for such fine work. another option is to fit 10BA studding easily made, and fit nuts into counterbored recesses rather than screw heads. this rather begs the question how long are your screws, and what are they for?

cheers,

julian

Hot and cold heading is the standard way industry makes bolts and screws.... So it will work if the screw is supported and the head forming die is nicely formed.

Industry usually forms the thread after the heading operation. I have been thinking about this job overnight. Maybe the threaded rod to be headed could be supported in a threaded hole. However I guess after heading it would deform and rivet itself in place? Maybe the answer would be to make the supporting die from two pieces creating a split die, Not that hard to do just put two rectangular pieces in the four jaw, centre them and bore and tap the join then face and turn the outside ID to the size of the nominally 12mm die holder, That way you could retrieve the screw after heading.

Regards
John

Yes, I probably should have given more detail in the first place - sorry.

The screws are 1 inch long, threaded 10BA (~1.6MM) over 6mm ish. Some will be threaded to the head.

Material is Nickel Silver

I need 24 in total and they are the spokes for two replica fishing reels (based on old Aerials), so they need to be straight and aesthetically excellent as they are visible.

I want to form the head first, then I'll thread.

Funny though, I've completed all the machining for the other components without real problems and these spokes, which I thought would be easy, are a nightmare. Couldn't even find the material in the straight condition, only coiled, so I ended up making a roller straightener to get this far.

Anyway, enough of my snivelling, I am in the workshop again tonight so I will make a jig as per John's first suggestion with an ejector rod against a grub screw at the bottom of the shaft hole. I'm thinking I may hit the head with one punch first, but if I need to I'll use two progressive shapes to keep it more concentric. This construction is nice and simple and should let me make it more accurately than my previous attempts.

My lathe (or it's operator) is not capable of machining this diameter between centres, unfortunately. I did wonder about splitting the die laterally as you suggest John, which could still be a possiblity, but I'm concerned about getting it accurate.

Will let you know how it pans out.

Cheers - Will

hi paul/will,

my stock of nickel silver is drawn rod and is quite brittle, so you will need to carefully anneal same i guess. ive made up nickel silver rivets for attaching stainless door hinge straps onto smokebox doors and if not annealed first the heads split and fracture.

good luck!

julian

Have you tried Deacon Screws [email protected]? That is RLDeacon

What about a travelling steady or one of those toolpost mounting steady/cutting combo tools? Shouldn't be a problem.

Great to hear Will.

A good wallop and the jobs done.....

regards
John

Some years back we had a spate of screws that the heads would just snap off, it transpired that they were Nickel silver. Be aware that the screws you are making will have very little tensile strength and will need care that they do not take a lot of strain. They become very brittle. The way the materiel is formed will have a great bearing on this.

Clive

Clive, would heat treatment over come the weakness caused by the cold heading? Ian S C

Nickel Silver does not contain silver it is a copper alloy.

Wiki:

**LINK**

Heating to a dull red and quench to soften it from the following search:

It looks like it does work harden rather abruptly.

**LINK**

Regards
John

Hello Ian, the screws on the Instruments would come in for service and repair and we would find that the slotted heads had split apart and you could see crystalline fracture. The factory changed the type of metal to what I know not, but after that we had no problems. Age I think may have something to do with it as well so age hardening possibly? They were CuNi in the parts list. I would think that they were machine cut on auto machines and bought in to spec. I still have some and they look more 'Brassy' than copper colour.

Now of course its all S/steel TORX or S/steel Skt head screws all torque set. We seldom see slotted screws anymore. Even grub screws are now steel.

Of interest a lot of the main bearings on the telescopes and standing axis are Alu. and have a ground finish. They are anodised and it has a polished surface. We are also getting Ceramic bearings now on the self pointing Theodolites as they orient themselves very quickly now.

Clive